“Scott Pruitt is stuck in the polluting past, and California is showing the way to a cleaner, profitable future — we are ahead of the rest of the nation in economic growth and in lowering emissions,” Schwarzenegger told Yahoo News in an email on Monday. “In the United States, we have a long history of instituting emissions standards to clean our air that goes back to when Richard Nixon was president and Ronald Reagan was governor of California. Those aren’t the most liberal guys around, let me remind you.”

Gov. Jerry Brown, Schwarzenegger’s successor, announced on May 1 that California is leading an 18-state coalition to sue the EPA in defense of the clean-car rules. The lawsuit alleges that the EPA “acted arbitrarily and capriciously, failed to follow its own regulations and violated the Clean Air Act.”

Under the Clean Air Act, California has the authority to set its own standards for vehicle emissions as long as they aren’t weaker than the federal standards, but the state is required to have a waiver from the EPA. That arrangement is predicated on the fact that, since the 1950s, California has set its own emission standards. Section 177 of the Clean Air Act allows other states to follow California’s standards instead of the federal requirements.

Schwarzenegger continued: “We also have a long history of the federal government respecting California’s right, as a state, to regulate our own air. When I was governor, the EPA thought they could stop us, and we won. The EPA even tried to claim that greenhouse gases were not a pollutant, and we took them all the way to the Supreme Court and we won that. Mr. Pruitt, I can assure you that California, and those who believe in a cleaner future, will win again.”

President Trump’s nomination of Pruitt as EPA chief elicited widespread condemnation from scientists and environmentalists, in large part because of his climate-change denial and close ties to the fossil fuel industry as attorney general of Oklahoma. Although support of Pruitt from conservatives has wavered amid allegations of extravagant spending and other ethics violations, the EPA chief has made it clear during congressional testimony late last month that he intends to fulfill Trump’s agenda of deregulation, including dismantling vehicle emission targets.

“It’s bad for the automakers because of the uncertainty it creates. It’s bad for consumers because it will cost them more money at the pump. And it’s bad for public health because it will increase pollution,” Tonachel said.

The standards Pruitt is targeting were enacted by the Obama administration in 2010. The EPA, the Department of Transportation’s National Highway Traffic Safety Administration and the California Air Resources Board established a national program of greenhouse gas emission standards for 2012-2025 vehicle models. The idea was to simplify automobile manufacturing by providing a single target while reducing air pollution. Based on extensive research, the EPA and CARB last year reaffirmed that these standards were appropriate.

Sen. Tom Carper, D-Del., ranking member of the Senate Committee on Environment and Public Works, got his hands on a draft of Pruitt’s new proposed regulations and, in a May 1 letter to Transportation Secretary Elaine Chao and Pruitt, urged them to abandon the “extreme and legally questionable” plan.

“Such a proposal, if finalized, would harm U.S. national and economic security, undermine efforts to combat global warming pollution, create regulatory and manufacturing uncertainty for the automobile industry and unnecessary litigation, increase the amount of gasoline consumers would have to buy and runs counter to statements that both of you have made to Members of Congress,” Carper wrote in his letter.

Asked for a response to Carper’s argument, the DOT’s National Highway Traffic Safety Administration responded that it is continuing to work with the EPA on the Corporate Average Fuel Economy and tailpipe standards for future passenger cars and light trucks.

“NHTSA’s top priority is safety and this Administration must also consider economic practicability when setting these Standards. The Department is committed to a public, robust, and transparent review process,” the agency said via email.

NHTSA will propose the next set of standards for public review and comment before they are finalized: “The agencies intend to take comment on a broad range of options. Given that the work is ongoing, at this time there is nothing to announce until a proposal is actually released.”

After Trump’s election, automakers requested that the EPA loosen the Obama-era standards, arguing that they didn’t take into account fuel-saving technology that could be used as credits to meet their quotas. But it appears Pruitt’s forthcoming rules will go far beyond what the industry had sought, and that’s a problem.

“They had regulatory certainty. Now they’re facing regulatory pandemonium,” Tonachel said. “At this point, the automakers have already done a lot of work to design the technology and product-plans for future model years.”

Tonachel said the automakers have made it clear from the beginning that they’d prefer to have a program that ensures they would be complying with all standards if they comply with one set.

The auto manufacturers certainly don’t want to be perceived as siding with polluters in a clash between Pruitt and roughly 43 percent of the automotive market. The plaintiffs include California, Connecticut, Delaware, District of Columbia, Illinois, Iowa, Maine, Maryland, Massachusetts, Minnesota, New Jersey, New York, Oregon, Pennsylvania, Rhode Island, Vermont, Virginia and Washington.

Bill Ford, executive chairman of Ford Motor, and Jim Hackett, the company’s president and CEO, released a blog post on March 27 saying they support increasing clean car standards through 2025, and have not asked for a rollback.

“We want one set of standards nationally, along with additional flexibility to help us provide more affordable options for our customers. We believe that working together with EPA, NHTSA and California, we can deliver on this standard,” they wrote.

Robert Bienenfeld, assistant vice president in charge of environment and energy strategy at the American Honda Motor, a subsidiary of the Japanese corporation, similarly told the New York Times last month, “We didn’t ask for that. The position we outlined was sensible.”

Tonachel said, “Ford and Honda are out there at some level expressing where they had hoped this was going to go. But it’s nowhere consistent with holding constant at 2020 levels.”

Neither the Association of Global Automakers nor the Alliance of Automobile Manufacturers, trade groups for automobile manufacturers that build and sell products in the U.S., responded to a request for comment.